/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.shardingsphere.governance.core.state;

import org.apache.shardingsphere.governance.core.registry.RegistryCenterNodeStatus;

import java.util.Deque;
import java.util.Optional;
import java.util.concurrent.ConcurrentLinkedDeque;

/**
 * Governed state.
 */
public final class GovernedState {
    
    private final Deque<RegistryCenterNodeStatus> states = new ConcurrentLinkedDeque<>();
    
    public GovernedState() {
        states.push(RegistryCenterNodeStatus.OK);
    }
    
    /**
     * Add state to stack and return.
     * 
     * @param state state
     * @return current state of instance
     */
    public RegistryCenterNodeStatus addState(final RegistryCenterNodeStatus state) {
        states.push(state);
        return getState();
    }
    
    /**
     * Get the current state of instance.
     * 
     * @return state
     */
    public RegistryCenterNodeStatus getState() {
        return Optional.of(states.peek()).orElse(RegistryCenterNodeStatus.OK);
    }
    
    /**
     * Recover state to the previous and return the current state of instance.
     * 
     * @return current state of instance
     */
    public RegistryCenterNodeStatus recoverState() {
        states.pop();
        return getState();
    }
}
